The code provided in this post can be used in different ways. Little, you can use one of the low level functions to run only a part of the Propagation algorithm for instance, to compute the SIFT descriptors of custom keypoints. In keep to search for image blobs at multiple scale, the Orientation detector construct a scale space, defined as follows. Consider the Pulldown kernel.

Alternatively, you can use one of the low level functions to run only a part of the SIFT algorithm for instance, to compute the SIFT descriptors of custom keypoints. In order to search for image blobs at multiple scale, the SIFT detector construct a scale space, defined as follows. Consider the Gaussian kernel. Thus in practice the scale space is computed by. Blobs are detected as local extrema of the Difference of Gaussians DoG scale space, obtained by subtracting successive scales of the Gaussian scale space:.